In a semiconductor device manufacturing process, a substrate processing apparatus that performs a predetermined process such as etching or film deposition on a substrate such as a semiconductor wafer (also simply referred to as “wafer” hereinafter) may be used, for example. Such a substrate processing apparatus may include plural processing apparatuses for performing predetermined processes on a wafer, transfer apparatuses that are connected to the processing apparatuses, and relay chambers (pass chambers) that are arranged between the transfer apparatuses (See e.g., Patent Document 1).
In such a substrate processing apparatus, a wafer may be transferred to/from the processing apparatuses by transfer arm mechanisms that are arranged at the transfer apparatuses, and the wafer may be transferred between the transfer apparatuses via the relay chambers so that the wafer may be successively processed by different processing apparatuses without being exposed to the atmosphere.
As illustrated in Patent Document 1, for example, the relay chamber typically has a stage (buffer) arranged inside its chassis so that a wafer may be temporarily placed thereon to facilitate exchange of the wafer between the transfer arm mechanisms of the transfer apparatuses. For example, in the case of transferring the wafer from one transfer apparatus to another transfer apparatus, the transfer arm mechanism of one transfer apparatus may transfer the wafer into the chassis of the relay chamber and place the wafer on the stage, and the transfer arm mechanism of the other transfer apparatus may pick up the wafer placed on the stage.